[fusslo]

I love these long-form build logs.

I just started reading, and I am making the faux-pas of commenting before finishing.

But, I'm wondering what the challenges are of automating the ROV to map a body of water's floor in a pattern. like a grid pattern, or whatever is most efficient.

At first I was thinking currents would cause displacement. but can't we sense the current moving us in undesirable ways and correct with thrusters?

And then I thought.. do lakes have currents? Do they have tides? can a ROV sense the boundary of a lake?

just further down the rabbit hole, realizing how little I've learned about the natural environment!

[tetha]

Lübecks university has several projects[1] using swarms of robots for automatic cartography, water measurements and such.

Autonomous accurate navigation under water is quite complicated, because after a certain point you need to start relying on local sensors because nothing reaches you anymore. But local sensors tend to be weird, because a straight line underwater is not necessarily a straight line - you are most likely drifting -- and detecting drift isn't easy. From a local observer, the water around you isn't even moving. That was a fun team to talk with.

1: https://www.iti.uni-luebeck.de/en/research-areas/mobile-robo...

[fusslo]

so cool; thank you for the link

[jarofgreen]

Lakes can have currents.

I wonder if pedantically speaking the definition of lake would include non-tidal in many countries but ....

A) humans use names sloppily and if it's an important detail I wouldn't assume a lake is non-tidal without checking.

B) non-tidal bodies of water might still change height over the year, for example after a heavy rainfall.

Mainly I'd question the need to automate it. It's difficult, and in many cases the cost of a human to drive it is tiny compared to all the other costs you need to pay so just do that (as in the article - those weren't automated). Also, driving them can be fun :-)

[eythian]

Rarely (as far as I know), lakes can be tidal in their own way. For example Lake Wakatipu changes by about 10cm every half an hour.

[relaxing]

My brother in christ we cannot even keep a robot on land rolling in a straight line without an external source of ground truth.

The way to do it is have a boat with GPS tow your sensor array.

[rkangel]

Note that ROV stands for Remotely Operated Vehicle - it is not autonomous, it is controlled by a person.

What you are describing would be called a UUV (unmanned underwater vehicle) or AUV (autonomous underwater vehicle).